Large shoring project in North America using hollow core injection anchors
An impressive excavation and shoring work was executed to make way for three residential/commercial buildings on False Creek, Vancouver. The project is the first stage of a huge development project called Concord Pacific Place, which will create over 1 million m3 of developed surface over the next eight to ten years. Twelve hundred DYWI® Drill Hollow Bars were used to secure the sheet pile walls in the 110,000 m3 excavation site.
The size of the excavation, the tight construction schedule and the ground conditions made this type of anchor the best choice. The DSI anchor system allows tie back anchors to be installed in soft, unstable soils eliminating traditional cased drilling methods. At the Concord Pacific site the ground is composed of clay-till with a high water table.
The DSI anchor system makes it possible to drill and insert anchors in one step while simultaneously injecting cement grout through the center of the self-drilling anchor rod. A "lost" cross drill bit at the end of the anchor rod uses a rotary percussive hammer motion to push and rotate the anchor rod through a hole in the sheet piling into the ground.
After three days for the grout to harden, the inclined R38 (Ø38 mm/1-1/2") anchors are stressed to 300 kN. The lengths ranged between 9 and 24 m. A 6 m long cement-grouted bond length anchored the rod into the underlying hard till strata. All DSI anchor rods were supplied in 3 m lengths and coupled on site to the required length of the anchor.
An average of 180 to 300 m of anchors was installed each day. The substitution of the commonly used cased drilling method with the DYWI® Drill core method paid off with an extremely high productivity. Production rates can be up to 5 times higher than the cased drilling method. In addition the very light and flexible drill rig made the DSI anchor system particularly easy to install.
The excavation and shoring work took eight weeks and was completed to the full satisfaction of the client.